FIG. 13 shows a layer configuration of a conventional in-mold molding film. The in-mold molding film is a continuous film, and mainly includes a carrier film 202 that is not transferred to a molded product, and a transfer film 203 that is transferred to the molded product. An in-mold molding film shown in FIG. 13 includes a coloring layer 105 that expresses predetermined design such as color, picture or pattern, and is used for decorating a surface of the molded product. Such an in-mold molding film used for decorating a surface of a molded product with predetermined design is referred to as a decorative film.
In-mold molding is a method for integrally molding a transfer film and injection molding resin in a mold to produce a molded product including a surface and a transfer film on the surface, and for example, used for decorating a surface of the molded product with various pictures. Specifically, in the in-mold molding, the transfer film is conveyed into the mold by a carrier film and mounted to the mold, and then molten injection molding resin is injected toward the transfer film in the mold.
The in-mold molding is used for producing audio-visual equipment such as television sets or audio devices, cellular phones, or the like.
In some decorative films, two-part curable ink having high heat resistance and high coating hardness is used as ink forming a coloring layer in order to prevent failure during injection molding such as ink flow or ink flying due to heat from molten injection molding resin or injection pressure of the molten injection molding resin. For example, see Japanese Patent No. 4052647. The two-part curable ink is prepared by adding a curing agent to thermoplastic resin.
A decorative film 201 shown in FIG. 13 will be further described in detail. A carrier film 202 includes a base film 101 that continuously supplies a decorative film 201 (transfer film 203) into a mold, and a delamination layer 102 for delaminating the transfer film 203 from the base film 101. As the base film 101, a PET film, an acrylic film, or the like is used. The transfer film 203 that is transferred to the surface of a molded product includes a protective layer or hard coat layer 103, an anchor layer 104, a coloring layer 105, a mask layer 106, and an adhesive layer 107. The protective layer or hard coat layer 103 protects the transfer film 203 from flaw or dust on an outermost surface of an in-mold molded product. The anchor layer 104 connects the protective layer or hard coat layer 103 and the coloring layer 105. The coloring layer 105 provides design such as color, picture, or pattern on the surface of the molded product. The mask layer 106 highlights the color of the coloring layer 105. The adhesive layer 107 bonds the transfer film 203 to injection molding resin. As described above, the decorative film 201 includes a plurality of layers.
Next, with reference to FIG. 14, a process for producing an in-mold molded product will be described. FIG. 14 shows a process for producing an in-mold molded product having a surface decorated with a decorative film.
First, in step S1, the decorative film 201 is fed by a foil feeding device 3 so that predetermined design such as color, picture, or pattern expressed by a coloring layer is placed in a predetermined position between a stationary mold 1 and a movable mold 2. At this time, the decorative film 201 is fed so that the base film 101 faces the movable mold 2, and the adhesive layer 107 faces the stationary mold 1.
After the decorative film 201 is placed between the stationary mold 1 and the movable mold 2, in step S2, the decorative film 201 is sucked through a suction hole 4 opened in a cavity surface of the movable mold 2 to mount the decorative film 201 to the cavity surface of the movable mold 2. Thus, the cavity surface is shaped by the decorative film 201. In step S2, an annular foil retaining member 5 secures the decorative film 201 to position the decorative film 201.
Then, in step S3, the movable mold 2 is moved to clamp the stationary mold 1 and the movable mold 2. At this time, the foil retaining member 5 is housed in a housing recess 6 formed in the stationary mold 1.
Next, in step S4, molten injection molding resin 8 is injected from a gate 7 of the stationary mold 1 toward the adhesive layer of the decorative film 201, and thus the molten injection molding resin 8 is poured into a cavity formed by clamping the stationary mold 1 and the movable mold 2. Thus, the molten injection molding resin 8 fills the cavity.
After filling of the molten injection molding resin 8 is completed, in step S5, the molten injection molding resin 8 is cooled to a predetermined temperature and hardened.
Then, in step S6, the movable mold 2 is moved to open the stationary mold 1 and the movable mold 2. At this time, the transfer film 203 adhering to the surface of the hardened (molded) injection molding resin 8 is delaminated from the carrier film 202. Thus, an in-mold molded product 9 having a surface to which only the transfer film 203 is transferred can be obtained. The obtained in-mold molded product 9 is coated with the protective layer or hard coat layer of the transfer film 203.
Then, in step S7, an ejection pin 10 is pushed out through the stationary mold 1 to take out the in-mold molded product 9.
After taking-out of the in-mold molded product 9 is completed, in step S8, adhesion of the decorative film 201 (carrier film 202) to the cavity surface by suction through the suction hole 4 in the movable mold 2 is stopped in preparation for next molding, and then the foil feeding device 3 feeds the decorative film 201. Thus, predetermined design such as color, picture, or pattern formed on the coloring layer and used for the next molding is placed in a predetermined position between the stationary mold 1 and the movable mold 2.
The operations described above are repeated to continuously produce the in-mold molded products 9.